The purpose of this is pre-processing the sprite atlas mipmaps so speed isn’t an issue.
ah my bad.
Well you could write a shader to do it i suppose just multi sample and blend all the texels around a uv for each pixel you draw to and set the alpha yourself.
Edit
I have a 9 year old cpu side, huge imaging class, that has a inch of dust on it, horrifys me to look at, Still works and has options i don’t even know what they do.
When used on a heavily partially transparent and non transparent image shrunk by a non uniform amount.
Here is the result.
200x120
100 x 50
Ill zip it if you want it might be easier though to just write your own shader how you like the alpha to work.